4.3L TBI on 3.8L Engine ?

Joe Boucher jboucher at startext.net
Sun Oct 19 12:09:06 GMT 1997


At 12:03 AM 10/18/97 -0400, you wrote:
>There is no way that a 4.3 manifold will fit a 3.8 engine.  The 3.8 is a
>Buick design, and the 4.3 is 3/4 of a small-block Chevy.  The architecture of
>each is totally different.  However, both are 90 degree designs.
>

I think we're loosing the bubble here and have missed the intent of the
original post.  Mr. Alford asked if a cheap 4.3 TBI could be adapted to
a 3.8.  Taking the throttle body, wiring harness and the sensors off the
4.3 and adapting them to the 3.8 shouldn't be hard.  The worst part
would be making an adapter for the throttle body to replace the carb. 
(I'm assuming there is a carb on the 3.8, because if it has a tpi
set-up, why bother!)

The one show stopper problem is the distributor.  There is no practicle
way to adapt the 4.3 distributor to the 3.8.  However, for a long time
(most of the 80's) GM used the HEI distributor without vacuum advance,
or mechanical advance, and a seven wire module to control advance.   If
the 3.8 in question has the HEI, then there is a chance it can be used. 
Remove the vacuum can, put a screw through the mechanical advance
weights to freeze them, and bolt in the seven wire module.  The big
question is whether this module can work with the 4.3 ecm.

If Mr. Alford is really interested, we need to know the year models of
the equipment to assess the risks.  Then I'll have to dig through a box
of magazines to find the diagram for the seven wire module.  There would
be no guarentee about this either.  A lot of this is a crap shot of one
form or another.  You get an idea, study it, way the risks, research the
problems as best you can, close your eyes and jump.  Then solve the
problems you missed.  If anyone thinks this is as easy as upgrading your
radio, then you are in for frustration.  The swap of a TBI motor and
overdrive transmission into my Suburban took to two weeks longer than I
planned and then a very long time to overcome the electronic speedometer
interface I missed.  Live and learn.

Joe Boucher
'70 RS/SS Camaro   '81 TBI Suburban



More information about the Diy_efi mailing list